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Old 11-15-2012, 05:23 PM   #84
Scooby Specialist
Member#: 132389
Join Date: Nov 2006
Chapter/Region: BAIC
Location: SF Bay Area
2006 WRX Wagon SGM
2003 SV1000S, 2014 DL650


Originally Posted by NOT_2_SLOW View Post
Why do you think you need a fuel pump? It can be added to the list of items not needed.
Originally Posted by HinshawWRX View Post
STI's and WRX's use the same fuel pump. So why would you need one? Answer is, you don't.
I can't believe people are discouraging the OP from getting a new Walbro fuel pump. You guys should know better by now.
Here's what is going on:
- The OP's car has 86K miles, the cylindric/round fuel filter inline with the pump is dirty and needs changing and the pump itself has become tired pushing fuel through a dirty and clogged fuel filter. The sock filter that is plunging into the fuel is also dirty as well.
- So, at the very least, the OP will need to change both the sock filter and the cylindric/round fuel filter but, while he's in there, he should take this opportunity to upgrade the fuel pump as well.
- With a VF39/VF43/VF48, depending on *boost target towards redline* and *depending on target AFR towards redline*, the stock fuel pump will not be able to provide enough fuel !! I repeat it again, depending on boost target and depending on target AFR, the stock fuel pump will not make it.

Let's give a specific example. I'm running 15.5 psi of boost from a VF43 from 5500RPM to 6800 RPM and my target AFR is 10.7:1. Guess what ? The stock fuel pump couldn't do it. I was only getting 10.9:1~11.1:1 AFR at best. My 02 wideband sensor was perfectly calibrated, the stock fuel pump with 40K miles on the clock just couldn't deliver enough fuel.

So, OP, change your fuel filters and UPGRADE that fuel pump while you're in there.
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